The present invention is related to power systems, and in particular to a system and method for filtering electromagnetic interference (EMI) in active rectifier power systems.
Aircraft systems, such as motor drive systems, often require direct current (DC) power for operation. The main sources of power onboard aircraft are generally gas turbine engine driven alternating current (AC) generators. These generators provide polyphase AC power that must be converted into DC power for use in the motor drive and other DC systems. In order to convert the polyphase AC power from the AC power sources into DC power, active rectifiers are often used.
Active rectifiers, such as Vienna rectifiers for three-phase power systems, utilize switches in conjunction with diodes in order to provide efficient rectification. The DC output power of these rectifiers may be controlled using pulse-width modulation (PWM). When implementing PWM, a switching controller enables and disables the switches for the three phases of the Vienna rectifier at a selected frequency. This switching creates source frequency harmonics and EMI in the form of electrical current within the power system that can propagate back through the generator and into other aircraft systems. In some cases, EMI may be generated with larger than desired magnitudes at the frequency bands at or around harmonic frequencies of the selected switching frequency. It is desirable to minimize the effects of this generated EMI within these power systems.